History of Flight
On 20 September 2018, a Boeing 737-800 aircraft registered VT-JGS, operated by Jet Airways, was involved in a serious incident during a scheduled flight from Mumbai to Jaipur. The flight crew consisted of an Airline Transport Pilot Licence holder as pilot-in-command and a Commercial Pilot Licence holder as first officer. There were 166 passengers on board. The incident occurred at 06:30 hours Indian Standard Time.
The flight crew reported for duty at 04:35 hours and completed pre-flight medical checks. The pilot monitoring conducted a walk-around inspection with no abnormalities noted. The pilot flying aligned the Inertial Reference System, and pre-flight procedures were completed. Cabin crew briefing was performed, and before-start checks were completed. After engine start, ground equipment was disconnected, and before-taxi checks were carried out. Air Traffic Control granted permission to line up and instructed the crew to wait behind another departing aircraft. During the before-takeoff scan, the pilot monitoring did not verify the engine bleed switches position as part of the air conditioning checklist. The aircraft took off from runway 27.
At 1000 feet, Mumbai approach radar cleared the aircraft to flight level 90. The after-takeoff checklist was performed, but the pilot monitoring did not notice that both engine bleed switches were off. The aircraft was subsequently cleared to climb to flight level 110.
Pressurization Issue
While climbing through flight level 100, the pilot monitoring observed that the cabin rate of climb was 2000 feet per minute and the cabin altitude was increasing. The crew discussed this. Shortly after, the cabin altitude warning horn activated. The pilot flying called for oxygen masks, which both crew members donned.
The pilot monitoring selected the pressurization mode selector to manual, closed the outflow valve, and turned on the passenger oxygen switch. The pilot flying called for the Cabin Altitude Warning and Rapid Depressurization non-normal checklists. At that moment, the pilot flying noticed both engine bleed switches were off and turned them on. The crew did not declare an emergency. The aircraft descended to flight level 100. Air Traffic Control was informed of a return to Mumbai due to technical reasons. After removing masks, the crew checked with cabin crew for injuries; none were reported at that time.
Landing and Aftermath
Landing back at Mumbai was planned using the Flight Management Computer. During descent, a master caution warning for equipment cooling appeared. The aircraft landed on runway 27 and taxied to bay K1. During taxi, the pilot monitoring noted the outflow valve was closed and opened it. The pilot flying then selected pressurization mode to auto, causing condensation smoke in the cockpit for a few seconds. The cabin crew reported condensation smoke in the cabin and that some passengers were bleeding from the nose or had ear pain. The flight crew requested medical assistance at the bay. All passengers were deplaned, and injured passengers received medical attention.
Injuries
According to the report, 21 passengers reported bleeding from the nose or ear. Some passengers also complained of ear pain. No crew members or other persons were injured. The aircraft sustained no damage.
Probable Cause
The official investigation concluded that the incident was caused by the non-observation of the engine bleed switches in the off position by the pilot monitoring during the before-takeoff and after-takeoff checklists.
Additional Findings
The aircraft had undergone a layover inspection on 19 September 2018. The maintenance engineer assigned to the night shift was required to turn the bleed switches off before the task and then back on after completion. The engineer forgot to return the switches to the on position before releasing the aircraft for departure.